Heat- or photo-curing compositions containing a curing resin such as an epoxy resin are widely used as a material of laminated sheets, coatings, adhesives, photolithography, and the like. Among known curing resins are epoxy resins obtained from various epoxy compounds including aromatic epoxy compounds typified by bisphenol A diglycidyl ether; alicyclic epoxy compounds, e.g., 2,2-bis(3,4-epoxycyclohexyl)propane and 3,4-epoxycyclohexylcarbonyloxymethyl-3,4-epoxycyclohexane; and aliphatic epoxy compounds, e.g., ethylene glycol diglycidyl ether and glycidyl(meth)acrylate, and curing agents including polyamine compounds, polyhydric phenol compounds, and acid anhydrides.
In addition to the epoxy resins, photo-curing resins using dipentaerythritol hexaacrylate, etc. are also known.
In obtaining a cured product from these curing resins, it is necessary to control characteristics, such as glass transition temperature, water absorption, dielectric constant, impact strength, tensile strength, elongation in tension, and adhesion strength; and curing rate and curing conditions at the time of curing. For that purpose, the structure of compounds and the composition should be selected properly. In particular, cured products used in multilayer printed circuits are required to have a high glass transition temperature, excellent dielectric characteristics, and a low water absorption.
For laminate applications, epoxy resins enjoy broad use in view of the performance balance. Characteristics control by structural design of epoxy compounds is described, e.g., in Patent Document 1 and Patent Document 2. The publications teach that 2,2-bis(3,4-epoxycyclohexyl)propane has a high glass transition temperature and propose using the compound in photolithographic applications or laminate applications.
Patent Document 1: JP-A-5-105896
Patent Document 2: JP-A-11-255863